Although performance and durability are highly desirable characteristics for dental replacement and repair work, for example, they alone are not the sole concern for practitioners and patients. Aesthetic value, or how dental materials look inside the mouth is just as desirable. For example, in prosthodontics and restorative dentistry, where tooth replacement, or prostheses, are custom made to fit in or on a tooth structure, there are instances where the restoration or repair can be seen from a short distance when the mouth is open. Thus in those instances, it would be highly desired that the dental material be nearly indistinguishable from adjacent tooth structure.
Prosthetics and restorative dentistry encompass the fabrication and installation of, for example, restoratives, replacements, inlays, onlays, veneers, full and partial crowns, bridges, implants, and posts. Conventional materials used to make dental prostheses include gold, ceramics, amalgam, porcelain and composites. In terms of aesthetic value, it is perceived that porcelains, composites and ceramics look better than amalgam and metals, since a prosthetic made from those nonmetals better matches or blends in with the color of adjacent natural teeth.
Various processes and procedures for creating or fabricating prostheses are now available to practitioners. Typically, a prosthesis is produced from a cast model made to replicate a dentition or through the use of computer automation is combined with optics, digitizing equipment, CAD/CAM (computer-aided design/computer aided machining) and mechanical milling tools. Fabrication of a prosthesis using a CAD/CAM device requires a “mill blank,” a solid block of material from which the prosthesis is cut or carved. The mill blank may be made of ceramic material. Typical ceramic blanks generally require a practitioner or laboratory to hold a large inventory of blanks in various shades due to their opacity and pre-determined color/shading. It would therefore be advantageous to have a mill blank with no pre-determined color and the ability to blend with or color-match the dentition surrounding the milled prosthesis. Providing such a mill blank would eliminate the need for having a large inventory of blanks in varying colors and shades, and give the practitioner the flexibility to color-match a prosthesis with the use of just one mill blank.